JPS6189930A - Supercharging pressure controller of exhaust turbo supercharged engine - Google Patents

Abstract

PURPOSE:To supply pressure intake air for the purpose of improvement of power generation when supercharging pressure is controlled by operation of both an exhaust bypass valve and an intake bypass valve by placing the supercharging pressure under the control of the intake bypass valve only if the quantity of intake air does not reach a set value. CONSTITUTION:An intake bypass valve 18 which opens and closes a blower bypass passage 17 is disposed in an intake passage 3. An exhaust bypass valve 15 which opens and closes a turbine bypass passage 14 is disposed in an exhaust passage 4. Before the quantity of intake air reach a set value, the exhaust bypass valve 15 is kept closed but the intake bypass valve 18 only is opened to releave pressure intake air so as to control supercharging pressure. If the quantity of intake air exceeds the set value, the exhaust bypass valve 15 only or both the valve 15 and the intake bypass valve are used for controlling supercharging pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a boost pressure control device for an engine equipped with an exhaust turbo supercharger.

(Prior Art) Conventionally, in an engine equipped with an exhaust turbo supercharger consisting of a turbine driven by engine exhaust gas and a blower connected to the turbine to pressurize intake air,
If the supercharging pressure of pressurized intake air supplied to the engine becomes too high, it will cause a decrease in engine durability, etc.
In order to regulate the maximum boost pressure, for example, Japanese Patent Application Laid-Open No. 57-1
As seen in No. 46023, a turbine bypass passage is provided to bypass the turbine of the exhaust turbo supercharger, and an exhaust bypass valve (wastegate valve) provided in this turbine bypass passage bypasses exhaust gas to increase the boost pressure. Control techniques are known.

Further, a technique is also known in which a blower bypass passage is provided to bypass the blower of the exhaust turbo supercharger, and pressurized intake air is relieved by an intake bypass valve provided in the blower bypass passage to control the supercharging pressure.

Therefore, the pressurization efficiency on the blower side of an exhaust turbo supercharger decreases as the intake air temperature increases, and this intake air temperature varies depending on the driving conditions of the flow mountain and supercharging pressure. It will change depending on the heat exchange with or the compression ratio. This efficiency is determined by the relationship between the flow rate of pressurized intake air fed according to the performance of the exhaust turbo supercharger and the boost pressure, and the direction in which it spreads from a certain point (point N in Figure 2). As a result, the temperature rises and the efficiency decreases.

When controlling the boost pressure of the pressurized intake air supplied to the engine, the required intake air amount changes depending on the engine operating condition, and the control is performed to obtain a substantially constant boost pressure in response to this. ing. Control of supercharging pressure by the exhaust bypass valve includes:
A part of the exhaust gas (exhaust energy) is bypassed and the blower driving force is adjusted to control the blower driving conditions such that the required flow rate can be obtained at the set boost pressure. In particular, the required flow ω is more important than the relationship between the most efficient flow rate and boost pressure.
If it is lower than that, the blower drive energy is correspondingly reduced to maintain the supercharging pressure and reduce the flow mountain, which causes an increase in the intake air temperature and a decrease in efficiency.

In addition, in the case where the boost pressure is controlled by an intake bypass valve, the blower is driven by exhaust energy corresponding to the required flow rate. It lowers the boost pressure, and if the flow rate is higher than the relationship between the most efficient flow port and the boost pressure, the amount of intake air relief will be large, the intake air temperature will rise, and the efficiency will decrease. It is something to do.

(Object of the Invention) In view of the above circumstances, the present invention provides an exhaust turbo supercharger that drives the exhaust turbo supercharger with high efficiency in various operating conditions in order to control the supercharging pressure by the exhaust turbo supercharger. The purpose of this invention is to provide a supercharging pressure control device for an engine with an engine.

(Structure of the Invention) The boost pressure control device of the present invention includes an exhaust bypass valve that controls boost pressure by bypassing exhaust gas in a turbine bypass passage that bypasses the turbine of an exhaust turbo supercharger, and An intake bypass valve is installed in the blower bypass passage that bypasses the blower of the turbocharger to control the boost pressure by relief of pressurized intake air, and the intake air amount 'c up to the set intake amount is controlled by the blower bypass. This is characterized by an intake bypass valve provided in the passage.

(Effects of the Invention) According to the present invention, when controlling the supercharging pressure by operating both the exhaust bypass valve and the intake bypass valve, the exhaust gas in J3 is adjusted to the most efficient relationship between the blower flow rate and the supercharging pressure. When the intake air amount reaches the set intake air amount ω corresponding to the uncontrolled blower flow rate corresponding to the energy, the exhaust bypass valve is closed and the boost pressure is controlled by pressurized intake air relief from the intake bypass valve only, and the intake air amount beyond this value is At the intake port, the boost pressure is controlled by the exhaust bypass valve or only the exhaust bypass valve, improving the efficiency of the exhaust turbo supercharger at each intake port and effectively increasing the output by supplying pressurized intake air. It is possible to obtain an improvement effect.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the overall configuration of an engine with an exhaust turbo supercharger, in which each cylinder 2 of the engine 1 is connected to an intake passage 3 and an exhaust passage 4, respectively.

In the intake passage 3, an air cleaner 6, an aflow meter 7, a blower 8a of an exhaust turbo supercharger 8, a throttle valve 9, and an intake manifold 11 equipped with a surge tank 10 are arranged in order from the upstream side and connected to each cylinder 2. and introduces intake air.

On the other hand, in the exhaust passage 4, exhaust gas from each cylinder 2 is collected in an exhaust manifold 13, and is discharged to the atmosphere through a turbine 8b of an exhaust turbo supercharger 8.

Above exhaust turbo supercharging! A turbine 8b is driven by exhaust gas from the engine 1, and intake air is pressurized by a blower 8a connected to the turbine 8b.

The exhaust passage 4 has a turbine 8b of an exhaust turbo supercharger 8.
A turbine bypass passage 14 is connected to bypass the
This turbine bypass passage 14 is provided with an exhaust bypass valve 15 that opens and closes the turbine bypass passage 14 .

The exhaust bypass valve 15 is connected to the turbine 8b1. : A part of the introduced exhaust gas is bypassed to the downstream side, and the turbine 8b is
The drive energy of the blower 8a is reduced by the engine 1.
This controls the boost pressure supplied to the

On the other hand, a blower bypass passage 17 that bypasses the blower 8a of the exhaust turbo supercharger 8 is connected to the intake passage 3, and an intake pipe pass valve 18 that opens and closes the blower bypass passage 17 is connected to the blower bypass passage 17. It is provided. A part of the pressurized intake air supplied from the blower 8a is relieved to the upstream side by the intake bypass valve 18,
The boost pressure is controlled by increasing the amount of air supplied by the blower 8a relative to the amount of air taken into the engine 1.

The exhaust bypass valve 15 is connected to a diaphragm-type exhaust side actuator 16 that operates its I1FJ I#J operation, while the intake bypass valve 18 is connected to an intake side actuator 19 that operates its opening/closing operation. The exhaust side actuator 16 is equipped with a spring 16a that biases the exhaust bypass valve 15 in the valve closing direction with a predetermined biasing force, and has a pressure introduction passage 20 in the pressure spring 16b.
is connected, and the discharge pressure (supercharging pressure) of the blower 8a is introduced as an operating source during the exhaust bypass valve 15. Further, the intake side actuator 19 includes a spring 19a that biases the intake bypass valve 18 in the valve closing direction with a predetermined biasing force, and the pressure chamber 19b is connected to the pressure introduction passage 20, and the intake bypass valve 18 is connected to the pressure chamber 19b. The discharge pressure (supercharging pressure) of the blower 8a is introduced as the opening operation source.

Furthermore, a first solenoid valve 21 is disposed in the pressure introduction passage 20 to open the exhaust side actuator 16 to the operating pressure or to the atmosphere, while the intake side actuator 1
A second solenoid valve 22 for introducing operating pressure or opening to the atmosphere is disposed at 9 . The opening and closing operations of the first and second solenoid valves 21 and 22 are controlled by control signals from a control unit M23 (control unit). - The intake air amount signal from the air flow meter 7 is input to this control device 23, and the control device 23 is in a state where high efficiency of the exhaust turbo supercharging 18 can be obtained by exhaust bypass or intake air relief according to this intake air amount. It controls boost pressure.

The above fli! The operation of the first and second solenoid valves 21, 22 by the control device 23 is set based on an efficiency map corresponding to the relationship between the flow IQ and the boost pressure P shown in FIG. In this efficiency map, point N is the point where the exhaust turbo supercharger 8 has the highest efficiency, and the same efficiency points spread out in an elliptical shape around this high efficiency point N. Efficiency decreases. The upper limit Pl of the boost pressure is set in conjunction with the performance of the engine 1 so as to pass through the high efficiency point N.

The upper limit P1 of the boost pressure is determined by the exhaust side actuator 16.
The discharge pressure of the blower 8a is set by the strength of the springs 16a and 19a of one intake side actuator, and the discharge pressure of the blower 8a is set by the pressure introduction passage 20 to the exhaust side actuator 1.
6 or into the pressure chamber 16b or 19b of the intake side actuator 19, the supercharging pressure reaches this set value P.
When it is higher than 1, this spring '16a or 19
The exhaust bypass valve 15 or the intake bypass valve 18 opens against the pressure a, and the supercharging pressure is regulated to the set value P by bypassing the exhaust gas or relieving the intake air.

In addition, the straight line A shows the increase characteristic of the supercharging pressure P with respect to the increase in the flow ff1Q in a state where both the exhaust bypass valve 15 and the intake bypass valve 18 are closed, that is, in an uncontrolled state. The highest limit of P will never cross this no-control line A. Each curve E drawn diagonally in parallel indicates that the exhaust energy is constant, that is, the turbine 8b
This shows the characteristics when the driving force is constant, and in the case of Jul-exhaust energy, as the flow ff1Q increases, the supercharging pressure 1] decreases.

Based on these characteristics, while the flow IQ increases, first or below the flow ωQ1 until the boost pressure reaches the set value P1, the first or second solenoid valve 21.22
Even if the bypass valves 15 and 18 are open, both bypass valves 15 and 18 are closed, and the supercharging pressure P increases along the uncontrolled line A.

Flow ωQ when the boost pressure reaches the set value Ps! From flow Q3 to flow Q3, that is, until flow ff1ch where the exhaust energy line Eo in which relationship between flow mQ0 and supercharging pressure P1 at the high efficiency point N reaches point a where it intersects with uncontrolled line 8,
Control is performed to close the first solenoid valve 21 and open the second solenoid valve 22 to improve efficiency. In other words,
For example, when the exhaust bypass valve 15 is opened to control the supercharging pressure P by bypassing the exhaust gas at the flow rate Q3, at this time, the exhaust turbo supercharging f118 is caused by the blower 8a feeding ω being the flow mQ3. It is driven under the condition that the supercharging pressure is set M P s, that is, at point b. On the other hand, a case will be described in which the supercharging pressure P is controlled by the intake relief in which the exhaust bypass valve 15 is closed and the intake bypass valve 18 is opened, as in the first embodiment. -5 Performing intake air relief means that the supply amount of the blower 8a is increased by the flow rate that flows into the blower 8a again through the blower bypass passage 17, and when the exhaust bypass valve 15 is closed, the intake air By increasing the flow IQ (discharge amount N) along the exhaust energy line Eo when the amount is 03 until the supercharging pressure P decreases to the set value Ps, that is, the flow port Qo at the high efficiency point N and the supercharging Blower 8 of exhaust turbo supercharging 18 at pressure Pt
a, the pressurized intake air is relieved by the intake bypass valve 18 by the flow rate of QOQ3=C11, and the intake air amount of the flow rate mQ3 is supplied to the engine 1. Therefore, compared to the efficiency at point b during exhaust bypass by the exhaust bypass valve 15, the efficiency at point N during intake relief by the intake bypass valve 18 is higher.

The same is true for the flow ffi Q 2 which is smaller than the flow rate Q3, and this flow fN Q 2 is a flow rate corresponding to the same exhaust energy line El as mentioned above, and when the exhaust bypass is used to control the supercharging pressure. In contrast to the drive of the exhaust turbo supercharger 8 at point 0, in supercharging pressure control by intake relief, the exhaust turbo supercharger 418 is driven at point b, and the intake air is relieved by the flow rate of Q3 Q2=Q2, and the engine The intake air amount to 1 is the flow ωQ2,
Efficiency is higher at point b than point 0.

Also, the flow rate is higher than the above flow ffl Q 3. Control is performed using both the opening operation of the first solenoid valve 21 and the opening operation of the second solenoid valve 22,
The exhaust turbocharger 8 is driven at point N by the exhaust bypass, and the intake air amount at point d is increased from this point N by intake relief.
Control is performed to obtain Qa, and the efficiency is improved by driving at the N point with respect to the d point.

On the other hand, if the flow rate exceeds the flow Qo, for example, the flow mQ
When it increases to s, a control signal is output to open the first solenoid valve 21 and close the second solenoid valve 22, and the exhaust turbo supercharging t18 is driven at point e by only the exhaust bypass.

At that time, if the exhaust bypass alone does not reach point e, intake relief is used in combination.

By controlling the operation of the exhaust bypass valve 15° and the intake bypass valve 18 by the control device @23 as described above,
It is possible to obtain higher efficiency of the exhaust turbo supercharging m8 than by controlling the supercharging pressure using only the exhaust bypass valve 15 or controlling the supercharging pressure using only the intake bypass valve 18.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an engine with an exhaust turbo supercharger according to an embodiment of the present invention, and Fig. 2 shows the flow rate and supercharging pressure of the exhaust turbo supercharger.
FIG. 1...Engine 3...-Intake passage 4...Exhaust passage 7...Air 70-Meter 8...Exhaust turbo supercharger 8a ...Blower 8b...Turbine 14...Turbine bypass passage 15...
...Exhaust bypass valve 16...Exhaust side actuator 17...
・Blower bypass passage 18...Intake bypass valve 19...Intake side actuator 16a, 19a
...Springs 16b, 19b...Pressure chamber 20...Pressure introduction passage 21...First solenoid valve 22...
・Second solenoid valve 23...control device

Claims (1)

[Claims] (1) An exhaust turbo supercharger consisting of a turbine driven by engine exhaust gas and a blower connected to the turbine to pressurize intake air, a turbine bypass passage that bypasses the turbine, and a blower bypass that bypasses the blower. a passage, an exhaust bypass valve provided in the turbine bypass passage to control boost pressure by bypassing exhaust gas, and an intake bypass valve provided in the blower bypass passage to control boost pressure by relief of pressurized intake air. A supercharging pressure control device for an engine equipped with an exhaust turbo supercharger, wherein the supercharging pressure is controlled by an intake bypass valve provided in a blower bypass passage when the intake air amount is up to a set intake air amount.